Update MbedOS and RIOT CI checkers to use `gcc-arm-none-eabi` on top of
ubuntu-latest
Upgrade to mbed-tools and mbed-os 6.17
Bump xtensa version to `2021r2-patch5` and re-enable `ESP_IDF_Build_Test`
JerryScript-DCO-1.0-Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu